1. Field of the Invention
This invention relates to an image recording device such as copying apparatuses, facsimiles, and so forth to copy or duplicate original documents. More particularly, the invention is concerned with a device for obtaining a multi-color recorded image by means of a plurality of recording heads for different colors disposed at different positions in the device, and by reading a plurality of different color information signals or introducing such signals from outside as inputs.
2. Description of the Prior Art
In recent years, there has been proposed an image forming device in which information from an original image are read out in bit unit by, for example, a self-scanning type light receiving element, etc., and then the information as read are converted into electrical signals, and the final image is digitally recorded in accordance with the thus converted signals. As the recording method thereof, there has been known the ink jet recording method.
When multi-color recording is to be carried out by the ink jet recording method, it is a usual practice to perform such recording with a plurality of (groups of) recording heads in conformity to the number of colors to be recorded (for example, with two sets of recording heads, one for red and the other for black, in the case of two-color recording in red and black), since it is difficult to do such polychromatic recording with a single (group of) recording head from the standpoint of feeding inks in various colors to the recording head.
In practicing the abovementioned multi-color recording, these two sets of recording heads cannot be too closely disposed. The reasons for this are that a certain degree of space interval is required between the heads for the sake of maintenance of the heads and due to bulkiness of the heads per se, a certain distance should be provided between the heads in accordance with the time period required for the ink in one color to dry up when it is recorded on a recording sheet so as to prevent mixing of red and black inks due to running, etc.
Accordingly, when the recording is to be done by simultaneously driving the two sets of red and black heads, it should be done by reading the information at two different points on the original, which correspond to the space interval between the heads and then transferring the signals as read out to the recording heads, not by recording the information at one and the same position on the original, while reading them.
On the other hand, as the method for reading the original in a bit unit and discriminating between red and black, there has been known a method of color discrimination by a color separation system such as, for example, a beam splitter, etc. This method is to split one and the same point on the original by means of the beam splitter into particular bands of spectroscopic wavelength, and to obtain intensity in the spectroscopic wavelength by light receiving elements for each of the spectroscopic wavelength bands as split.
Therefore, as the method for dichromatic recording using the ink jet heads and the abovementioned color separation system, there may be contemplated one method, wherein a two color splitting system is used for reading two points (or lines) on an original image corresponding to the space interval between two sets of the recording heads.
According to this method, however, two pieces of the light receiving element are required for each set of recording heads, hence, a total of four pieces (2 pieces.times.2 sets) of recording heads are required, thereby creating various disadvantages such as, a requirement for more space for accommodating these light receiving elements, the necessity for a more complicated circuit construction for driving these light receiving elements, and an increase in the working steps required for adjusting the positions for installing these light receiving elements etc. Furthermore, in a device which records external input signals in different colors at different positions, it is necessary that one of the color signals should be delayed for a space interval between the recording heads with the consequence that the address operations for writing and reading image information into and out of the recording device becomes disadvantageously complicated.